The present invention relates to an enzyme preparation comprised of highly heat-resistant nuclease active fractions present in the product of fungi. More specifically, the present invention relates to an enzyme preparation comprised of nuclease active fractions that will not lose their activity even after heating at 100.degree. C. for 30 minutes.
Various enzyme preparations comprised of cellulase produced by fungi are commercially available, among which are Cellulase Onozuka.RTM. (derived from Trichoderma and manufactured by Kinki Yakult Co., Ltd.), Cellulase AP.RTM. (derived from Aspergillus and manufactured by Amano Seiyaku Co., Ltd.) and Toyo Cellulase.RTM. (derived from Fusarium and manufactured by Toyo Jozo Co., Ltd.). These cellulose preparations are known to contain various enzymes that decompose polysaccharides or proteins. Some of these enzymes have already been isolated and their properties have been reviewed. Because of their nature, these cellulase-containing preparations are used extensively for decomposing polysaccharides and proteins. However, no attempt has been made to review the action these cellulase preparations and the products of fungi will exert on DNA. No knowledge has been obtained as to whether they have nuclease activity.
While a great number of enzymes have been known, most of them are labile to heat and their activity will decrease so greatly upon heating as to suffer a substantial loss in practical value. In particular, those enzymes which are capable of maintaining their activity even if they are heated at 100.degree. C. for 30 minutes and longer are almost nil. A need has, therefore, arisen for the development of enzyme preparations that are capable of maintaining their activity even if they are exposed to prolonged heating at elevated temperatures.